Highly efficient sum-frequency generation (SFG) in reverse-proton-exchanged (RPE) waveguides in LiNbO{sub}3 as a means of single-photon detection at communication wavelengths

摘要

Single-photon detection at wavelengths in the fiber-optic communications band has been studied for many years. The application of quantum cryptography requires compatibility with the standard telecom network, which operates near 1.55 μm, where fiber losses are minimized (< 0.2 dB/km). Current detection technologies operating at these wavelengths cannot deliver the performance needed to implement, for example, quantum key distribution as required by the BB84 quantum coding scheme. Two of the more prominent technologies currently used are InGaAs/InP avalanche photodiodes (APDs), and solid-state photomultipliers. Both suffer from low detection efficiencies (< 16% [1]) and high dark counts (> 10{sup}4/s). Furthermore, the operation of either of these devices requires liquid nitrogen cooling. On the other hand, single-photon detection in the near-infrared can be performed very efficiently using silicon APDs.